Early age properties of cementitious materials by electrical resistivity measurement

Abstract

Three cement pastes were prepared with the fixed water-binder ratio and different fly ash contents. The compression test and electrical resistivity measurement of the paste mixes were conducted during 48 h. The changes of the CH content and the non-evaporable water content in the cement-fly ash hydration systems with time were obtained by the thermal gravimetric analysis. The experimental results show that dilution effect of fly ash as micro-filler is dominant mechanism before 48 h, which appears to decrease in the CH content and the non-evaporable water content, also in compressive strength and electrical resistivity, with the increase of fly ash replacement. The relationships between CH content, non-evaporable water content and electrical resistivity show that electrical resistivity can be the indicators of hydration products CH and non-evaporable water. The correlation of the compressive strength f _c and the electrical resistivity ρ can be obtained as f _c=8.3429 ρ = 6.7088 for the period of 48 h. The early age compressive strength can then be predicted by electrical resistivity measurement.

Keywords

electrical resistivity / fly ash / compressive strength / hydration

References

[1] McCarter W.J. Monitoring Pozzolanic Activity by Direct Activation with Calcium Hydroxide[J]. Construction and Building Materials, 1996, 10(3): 179-184.

[2] McCarter W. J., Ezirim H. C. Monitoring the Early Hydration of Pozzolan-Ca(OH)₂ Mixtures Using Electrical Methods[J]. Advances in Cement Research, 1998, 10(4): 161-168.

[3] Tashiro C., Ikeda K., Inome Y. Evaluation of Pozzolanic Activity by the Electric Resistance Measurement Method [J]. Cement and Concrete Research, 1994, 24(6): 1133-1139.

[4] McCarter W., Chrisp T., Starrs G., Blewett J. Characterization and Monitoring of Cement-based Systems Using Iintrinsic Electrical Property Measurement [J]. Cement and Concrete Research, 2003, 33: 197-206.

[5] Wei X., Li Z. Early Hydration Process of Portland Cement Paste by Electrical Measurement [J]. Journal of Materials in Civil Engineering, 2006, 18(1): 99-105.

[6] Wei X., Li Z. Study on Hydration of Portland Cement with Fly Ash Using Electrical Measurement [J]. Materials and Structures, 2005, 38: 411-417.

[7] Li Z., Wei X., Li W. Preliminary Interpretation of Hydration Process of Portland Cement Using Resistivity Measurement [J]. ACI Materials Journal, 2003, 100(3): 253-257.

[8] Targan S., Olgun A., Erdogan Y., Sevinc V. Effects of Supplementary Cementing Materials on the Properties of Cement and Concrete [J]. Cement and Concrete Research, 2002, 32(10): 1551-1558.

[9] Lawrence P., Cyr M., Ringot E. Mineral Admixtures in Mortars Effect of Type, Amount and Fineness of Fine Constituents on Compressive Strength [J]. Cement and Concrete Research, 2005, 35(6): 1092-1105.